作者:Tania I. Houjeiry、Sarah L. Poe、D. Tyler McQuade
DOI:10.1021/ol301874x
日期:2012.9.7
Recently, Nicolaou and Baran independently synthesized optically active 4-substituted 2-cyclohexenones via an efficient LION-mediated intramolecular aldol condensation. Thus far, application of their cyclization approach has been limited to ketoaldehydes where the R-group is branched. It is demonstrated that the LiOH-mediated cyclization, when applied to substrates containing unbranched R-groups, results in significant erosion of optical purity. A mechanistic justification is provided, and a set of neutral, organocatalyzed conditions is identified that enables cyclization with little loss in optical purity.